Process for the production of refractory masses or bricks from slags



United States Patent i PROCESS FOR THE PRODUCTION OF REFRAC- TORY MASSESOR BRICKS FROM SLAGS Karl Albert, Vogelbeck, Hannover, Germany NoDrawing. Application May 14, 1952, Serial No. 287,810

1 Claim. (Cl. 106-55) The invention relates to a process for theproduction of highly refractory or refractory masses and/or bricks, allhereinafter called blocks.

It has been found that the resistance to wear, the durability and theresistance to change of temperature of such blocks can be considerablyimproved by comminuting slags which are poor in silicic acid (SiOz),especially those incorporating titanium and manganese, to the finenessof a flour up to a grain size of about .51, then mixing the same with abinder, such as wator-glass, moulding such mixture to the desired shapeand compacting it by pressing or shaking, and then subjecting themoulded products or the mass for a number of hours to a heat treatmentat temperatures of about 212-392 F. Suitable starting materials are theslags which contain the aforementioned high-melting point metals andsmall silicic acid content, and which occur in the crucible-steelprocess or in an electric furnace. Thermite slags of such compositionmay also be employed.

In the new cold-bonded slag blocks, the individual grains are connectedtogether with the aid of the binding agent by adhesion. The internalrelationship of the particles in the blocks is therefore very mobile.and can, on the subsequent insertion of the blocks in a furnace, adaptitself considerably better than the structure of calcined blocks to theheat stresses that act upon the surface of the smallest side of theblocks, since in calcined blocks, the individual granular constituentsare fritted together by sintering, so that a rigid and not very yieldingstructure is produced. This fundamental difference between thestructures of cold-bonded blocks and calcined blocks is substantiallymaintained when the blocks are used in industrial furnaces, since theblocks are exposed to high temperatures only on their sides exposed tothe fire, whilst the heating effect falls off rapidly at the other side.The special advantages of the cold-bonded blocks, particularly theirresistance to change of temperature and other advantageous properties,therefore remain unaltered in use.

Water-glass is employed as a binding agent for the basic material.

The cold-bonded blocks produced from titanium slags have proved to beparticularly advantageous, since, in addition to high resistance totemperature changes, as well as improved durability and resistance towear, they prevent the formation of scale to a very high degree. Theyare therefore especially suitable for lining parts of the furnaces whichare exposed to the formation of scale, so that, according to theinvention, they are employed especially for lining the annular zone ofLepol and other revolving furnaces as well as for lining the sinteringzone of shaft furnaces for the production of cement. When these blocksare employed, the considerable disadvantages, which hitherto occurred inthe zones mentioned owing to the formation of rings of scale, areeliminated. Presumably this may be attributed to the very lowheat-conductivity of the cold-bonded titanium 2 slag blocks, whichcauses a constant shedding. ofthe scale formed, so, that they cannotgive rise to the said rings of scale.

Example 1 Ferro-titanium slag, as it occurs in the Thermite proeess, andwhich has the following composition:

Water-glass is used as a binder.

Example 2 Slags of the following composition, which occur in theThermite process, are employed:

Percent SiOz 0 to 5 A1203 54 i0 F6203 l 5 to 1'0 TiOz. 15 to 33 CaO 2 m7MgO 2 to 7 The slags are comminuted to a mixture. having the aforesaidgrain sizes, and mixed with 4 to 8% by Weigh of water-glass (d=l.350) aswell aswater until the whole becomes mouldable, then compacted byshaking, pressing or stamping and subjected to a heat treatment for aperiod of several hours at 2l2-392 F. Blocks obtained in this way may beused for lining the ring zones of Lepol and other revolving furnaces asweli as the sintering zone of shaft furnaces for the production ofcement.

Example 3 A manganese slag of the following composition is used toproduce an extremely tough, wear-resistant, special block which istypified by a very high resistance to temperature variation incombination with highly refractory qualities:

Percent SiOz 1.5 to 3.5 A1203 61 to 63 F6203 1.0 to 2.3 M11304 10 to 14CaO 14 to 16 MgO 5.0 to 10 BaO to 1 This slag is comminuted and made upin the following granular composition:

724' to .l2" 30 to 35%. up to .l2" 35 to 70% including flour 25 to 30%.

The mixture thus obtained is mixed with approximately 7 per cent byweight of water-glass (d=l.350) and the quantity of water required tomake it plastic, and is formed into blocks by agitation or tamping. Themoulded bodies obtained are brought to bonded condition by a heattreatment, in which the temperature rises to 392 F., lasting for aperiod of about 24 hours.

The blocks produced are of high refractory quality besides possessing avery good cold compressive strength and. heat resistance.

Example 4 A mixture of two manganese slags, differing in their chemicalcompositions, are used to manufacture a block which is particularlysuited for use in rotary furnaces. The first manganese slag (hereinafterreferred to as slag I) has: the composition:

Percent SiOz 1.5 to 3.5 A1203 61 to 63 FezO: 1.0 to 2.3 MnaO4 to 14 CaO14 to 16 MgO 5.0 to 10 BaO to 1 and is mixed in equal parts with thesecond slag (slag ulation set out in Example 1, mixed with approximately6% water-glass (d=1.350) and the quantity of water required to render itplastic, moulded into blocks by shaking or tamping, and these blocksbonded by heating the blocks to a maximum temperature of 392 F. for 'aperiod of about 24 hours.

In comparison with the properties of the product of Example 1, theblocks here produced have, as befits their intended use, an even higherrefractoriness, heat resistance and toughness.

I 2 Example 5 whole or partial replacement of the finely-dividedcomponents of a mixture of slags of the composition and granularconstitution of Example 4 by titanium slags in flour form, a specialblock of great resistance to wear and breakage and to temperaturevariation is obtained.

To produce such a block the manganese slags described in Example 4 aremixed in equal proportions, the mixture comminuted, and mixed withfinely-divided titanium slag in approximately the following composition:

Percent .24 to .12 1 30 to 35 up to .12 112 35 to Flour 3 10 to 15 1Mixture of equal parts of manganese slags I and II. Including 10 to 15%flour. 3 Titanium slag.

Added to this mixture are at least 7 per cent by weight of water-glass(d=1.350) and the quantity of water re quired for plasticity, and thecomposition moulded into blocks and bonded as described above. Theblocks thereby obtained have an even greater wear and breakageresistance and heater refractory quality than those produced in Examples1 and 2, and a high degree of resistance to temperature variation. Theseattributes are achieved in augmented form if the whole of the flourcomponent is replaced by a flour of titanium slag.

I claim:

A method of manufacturing refractory masses and blocks, consisting ofthe steps of so comminuting high softening and melting temperature slagsof the type derived from the production of titanium in an electrofurnace and by the alumino-thermic reaction of titanium ores andconsisting of up to 5% SiOz, 54 to A1203, 15-33% TiOz, 1.5-10% FezOs,2-7% Ca(), and 27% MgO as to make said slags contain about 30% of acoarse component of .24" to .12 grain size, about 40% of a mediumcomponent of less than .12" grain size, and about 30% flour; mixing saidcomminuted slags with 4 to 8% by weight of waterglass having a densityd=1.350 for elastically bonding the slag particles and water in aquantity suflicient to bring the mixture into a moldable state;compacting said mixture; and heating said mixture for a period ofseveral hours at temperatures of 212 F. to 392 F.

References Cited in the file of this patent UNITED STATES PATENTS529,450 Kirchmann et al Nov. 20, 1894 1,094,876 Carson Apr. 28, 19141,244,688 Becket Oct. 30, 1917 1,462,991 Taylor July 24, 1923 2,252,317Goldschmidt Aug. 12, 1941 FOREIGN PATENTS 908 Great Britain 1878 119,101Great Britain 1918

